Scheduled qty on PO can exceed line item quantity on PR

When we create a PO based on a PR, the system allows the buyer to increase the amount of the line item quantity by adding additional scheduled lines to Delivery Schedule for PO line item, therefore going over the line item quantity of the PR. Is there a system config to always make sure PO line item qty is equal to or less than PR line item qty or is custom code needed. See screen shot for example.